Simon pollak



2 Sheets-Sheet 1.

(N0 Model.)

Patented June 28 U A \\\\\\\\\\\\\\\\\\\\\\\\\\\\\W y \I|lllllllllllllllllllllll U Fain/1MP W/ TN E S S E S ATTORNEYS,

' UNITED STATES! PATENT OFFICE.

sIMoN" POLLAK, OF PRAG AUSTBlA- HUNGARY, AssIenoR ro EM IL FRIEDHEI OF NEW YORK, N. Y.

ANTI-INDUCTIVE DEVICE FOR TELE PHONES.

' SPECIFICATION forming part of Letters Patent no. 477,870, dated June 28,1892. Application filed November 11, 1891. Serial No. 411,549. (No model.) Patented in Germany November 12, 1890, No. 58,513.

the voices of several speakers become 'audi ble. This induction is supposedto be due to the necessary parallelism of conductors which run close together, but to different stations; but it is mainly due to the action of the mi- 1 crophones at the central stationand at the end stations The aim of my invention is to enable any one using a telephone to prevent these induction noises and to regulate the instrument from time to time to overcome the effects of stronger currents or noises. I

In the drawings, Figure l is a diagram illustrating the principle of the invention. Fig.

2 is a plan view of my apparatus, Fig. 3, a"

plan view of same without the cover. Fig.4 is a longitudinal section of same.

The principle underlying my invention is the following: If an induction-coil S, placed in the line-circuit and receiving an induced current, Fig. 1, is gradually brought nearer to a second coil S, which is merely connected with the telephone-receiver T, and whose windings are parallel to those on S, then a strong induction noise will be noticed in the telephone. If S remains in its position and S is turned, as by dotted lines in Fig. 1, it will be noticed that the noise in'the telephone gradually diminishes, and as soon as the coil S occupies a position at right angles with its original position not the slightest noise will be noticed in the telephone; but as soon as the coil S is turned beyond ninety degrees or back the noise will gradually reappear. The weaker the induction noise the sooner it will disappear when the coil S is turned. If an apparatus of this kind'is inserted in a telephone-circuit, as in Fig. 1, then if induction noises are noticed at the receiving-station they will," by turning the coil s' or sliding the con s, or both,be entirely suppressed andstill leave the mainor direct conversation audible. I

The apparatus shown in the accompanying drawings is constructed on the principle represented in Fig. l, and mainly shows a sliding and also a pivoted coil, both placed in proximity to one another and within the reach of the receiver of a telephonic message.

S is a coil placed on a drawer or slide 8 within a box A. S is another coil suspended from a rod c or other pivot, so that it can be turned by turning the handle K. The wires 0)?) connect the telephonic receiver with the coil S, but are not in a battery-circuit, the

, receiver having only an induced current from the coil S through the coil S, and this induction-current can be varied in intensityby either turning the coil S on its pivots or re-' ciprocating the coil S on the slide 8, as heretofore described. The line-wires c d connect the coil S with-the transmitter and the earth, as in Fig. 1. If coils with primary and secondary wires are used, the ends of the primary wire must remain unconnectedf The rod 0 may be screwed into the boXA or its cover to be capable, also, of lifting or lowering the coil S.

The wires (1 6 maybe directly connected by a removable plug e, so that the above apparatus can be cut out when there are no objectionable noises by leaving the plug in place; but as soon as the noises appear the plug a is removed and the coils S S are thrown into action.

In case the induction noises are objectionable, the coil S is turned until the noises disappear entirely, or substantially so. Then a microphone battery may be inserted to strengthen the direct current.

Having described my invention, what I claim, and desire to secure by Letters Patent, 1s-

1. The combination, with ateleph ne transmitter on aline-circuit provided with an induction-coil, of a telephone-receiver adapted to receive and beoperated by an inductioncurrent, and an induction-coil on said telephone-receiver circuit adapted and arranged to receive an induction-current from the coil on the line-circuit and transmit the same to able and adapted and arranged to be brought [0 into and out of alignment with each other to an y desired degree, substantially as described, and for the purposes set forth.

SIMON POLLAK.

Witnessess FERDINAND FIALA. J OOEF DOLEZER. 

